T  P 


°F     ILL1NOIS     BULLETIN 


DECEMBER  22,  1908  No.   18 

;ond-class  matter  under  Act  of  Congress  July  16.  1894  J 


CIRCULAR  NO.  3 


FUEL  TESTS  WITH  ILLINOIS  COAL 

(COMPILED  FROM  TESTS  MADE  BY   THE  TECHNOLOGIC  BRANCH  OF  THE 

UNITED  STATES  GEOLOGICAL  SURVEY,  AT  THE  ST.  Louis  FUEL 

TESTING  PLANT,  1904— JUNE  30,  1907). 

BY 
L.  P.  BRECKENRIDGE 

AND 
PAUL  DISERENS 


UNIVERSITY  OF  ILLINOIS 
ENGINEERING  EXPERIMENT  STATION 


URJBANA,  ILLINOIS 

PUBLISHED    BY  THE   UNIVERSITY 


<? 


UNIVERSITY  OF  ILLINOIS 
ENGINEERING  EXPERIMENT  STATION 

CIRCULAR  No.  3  DECEMBER  1908 

FUEL  TESTS  WITH  ILLINOIS  COAL 

(COMPILED  FROM  TESTS  MADE  BY  THE  TECHNOLOGIC   BRANCH    OF  THE 

UNITED  STATES  GEOLOGICAL  SURVEY,  AT  THE  ST.  Louis,  Mo.,  FUEL 

TESTING  PLANT,  1904-JuNE  30,  1907.) 

BY 

L.  P.  BRECKENRIDG,.,  DIRECTOR  OF  THE  ENGINEERING  EXPERIMENT  STATION, 
ALSO  CONSULTING  ENGINEER,  TECHNOLOGIC  BRANCH,  U.  S.  G.  S. 

AND 
PAUL  DISERENS,  M.  E. 

CONTENTS 

Page 

I.  Introduction 2 

II.  A  Summary  of  Conclusions 2 

III.  The  Coals  Tested 4 

IV.  Chemical  Properties  of  the  Coals  Tested 9 

V.  Washing  Tests 18 

VT.     Coking  Tests 23 

VII.     Steaming  Tests 26 

VIII.     Producer-Gas  Tests 43 

357045 


EXPERIMENT    STATION 


I    INTRODUCTION 

The  United  States  Geological  Survey  Technologic  Branch  has 
conducted  at  the  St.  Louis,  Missouri,  fuel  testing  plant,  a  series 
of  investigations  on  the  fuels  of  the  United  States.  These  tests 
included  a  large  number  of  Illinois  coals.  The  results  of  the 
tests  have  been  published  from  time  to  time  in  a  series  of  govern- 
ment bulletins  which  contain  very  full  descriptions  of  methods 
and  very  complete  details  of  the  results  obtained.  A  complete 
list  of  the  government  bulletins  is  given  at  the  end  of  this  publi- 
cation. 

The  tests  included: 

(a)  Steaming  tests  under  boilers 

(b)  Producer-gas  tests 

(c)  Washing  tests 

(d)  Coking  tests 

(e)  Briquetting  tests 

(f)  Chemical  tests  for  composition  and  heating  values 

(g)  Field  work  tests,  sampling  tests  and  a  few  other  minor 
investigations. 

It  is  the  purpose  of  this  circular  to  present  in  compact  form 
the  important  results  of  the  government  tests  so  far  as  these  tests 
relate  to  Illinois  coals.  The  Engineering  Experiment  Station 
hopes  that  by  bringing  together  in  one  circular  the  tests  made  by 
the  government  on  Illinois  coals,  it  may  do  a  service  to  the  engi- 
neering, industrial  and  fuel  interests  of  the  State.  The  compiler 
has  presented  a  few  conclusions  which  seem  justified  by  a  study 
of  the  results  recorded  from  tests  already  made.  It  is,  however, 
fair  to  say  that  in  a  few  cases  the  number  of  tests  made  is 
scarcely  sufficient  to  warrant  any  general  application  of  the  con- 
clusions stated. 

II    A  SUMMARY  OF  CONCLUSIONS 

The  results  of  the  United  States  Geological  Survey  tests  of 
Illinois  coal,  presented  in  the  following  pages,  seem  to  justify 
the  conclusions  given  below. 

1.     The  chemical  properties  of  the  coals  tested  indicate  that 


FUEL  TESTS  WITH   ILLINOIS   COAL  8 

VG 

on  a  basis  of  the  volatile-carbon  total-carbon  ratio  (-77-),  all  Illi- 

G 

nois  coals  tested  belong  in  Class  B  or  Class  D*.  The  maxi- 
mum value  of  this  ratio  is  33.4  per  cent  and  the  minimum  value  is 
20.9  per  cent. 

2.  The  average  calorific  value  of  Illinois  coal  is  14319  B.  t.  u. 
per  pound  of  pure  coal  (ash  and  moisture  free).     But  few  samples 
tested  varied  from  this  value  by  an  amount  more  than  2  per  cent. 

3.  The  quality  of  Illinois  coal  is  greatly  increased  by  wash- 
ing.    The  reduction  in  ash  and  in  sulphur  is  as  follows:— 

When  raw  coal  contains  8%  ash,  the  reduction  in  ash  is  20%. 
When  raw  coal  contains  12%  ash,  the  reduction  in  ash  is  30%. 
When  raw.coal  contains  16%  ash,  the  reduction  in  ash  is  43%. 
When  raw  coal  contains  20%  ash,  the  reduction  in  ash  is  53%. 
When  raw  coal  contains  2%  sulphur,  the  reduction  in  sulphur  is  13%. 
When  raw  coal  contains  3%  sulphur,  the  reduction  in  sulphur  is  17%. 
When  raw  coal  contains  4%  sulphur,  the  reduction  in  sulphur  is  22%. 
When  raw  coal  contains  5%  sulphur,  the  reduction  in  sulphur  is  28%. 

4.  The  material  rejected  by  the  washing  jig  contains  I  coal 
and  i  noncombustible  refuse. 

5.  One-fourth  of  the  coal  tested  may  be  used  for  the  manu- 
facture of  coke. 

6.  The  evaporative  efficiency  of  Illinois  coal  when  burned  in 
a  hand-fired  furnace  under  a  water- tube  boiler  averages  62.7  per 
cent.    This  performance  compares  favorably  with  that  of  any  other 
bituminous  coal  tested  at  the  United  States  Geological  laboratory. 

7.  The  evaporative  efficiency  of  Illinois  coal  is  but  slightly 
affected  by  the  moisture  contained  in  it. 

8.  The  evaporative  efficiency  of  Illinois  coal  decreases  as  the 
ash  and  sulphur  increase.      Each  additional  per  cent  of  ash  and 
sulphur  results  in  0.4  per  cent  decrease  in  efficiency. 

9.  The  evaporative  efficiency  of  Illinois  coal,  when  burned  in 
a  hand-fired  furnace,   decreases  as  the  per  cent  of  fine  coal  con- 
tained in  it  increases. 

10.  Briquetting  improves  the  evaporative  efficiency  of  Illinois 
coal  only  when  the  raw  coal  is  in  the  form  of  slack  or  screenings. 

11.  The  performance  of  Illinois  coal  in  a  gas  producer  com- 
pares favorably  with  that  of  any  other  bituminous  coal  tested  at 
the  United  States  Geological  Survey  laboratory. 

12.  The  value  of  Illinois   coal   as   fuel  for   a   gas-producer 


*Professor  Parr's  classification  of  coal,  see  page  11  of  this  circular. 


4  ILLINOIS   ENGINEERING    EXPERIMENT   STATION 

decreases  as  the  ash  contained  in  it  increases  and  as  the  calorific 
value  decreases. 

13.  In  small  plants  it  requires  at  least  two  and  one-half  times 
as  much  coal  to  develop  one  horse- power  when  used  in  steam  boiler 
service  as  when  used  in  gas  producer  service. 

14.  Gas  producers  can  be  continuously  operated  with  Illinois 
coal  developing  one  electrical  horse-power  with  1.7  Ib.  of  dry  coal. 

Ill    THE  COALS  TESTED 

1.  The  mining  centers  and  districts  of  Illinois,  recognized  by  the 
trade  and  defined  with  reference  to  geographical  position,  have 
been  described  as  follows.* 

(a)  Williamson,  Franklin,  and  Perry  Counties.     Williamson 
County  led  the   production  of   the   State  in  1907  with  more  than 
5,500,000  tons.      No.  7,  the  Blue  Band  seam,  which  is  from  5  to 
10  feet  thick,  averaging  9  feet   over  a  large  area,  is  the  greatest 
producer.      It  maintains  an   approximate  uniformity  in  physical 
character  and  thickness  but  varies  from  place  to  place  in  fuel  value. 
At  Spillertown  another  seam,  4  feet  thick,   is  mined  60  feet  below 
No.  7.      This  seam  is  probably  equivalent  to   No.  5   of  Saline 
County  and  may  have    a    wide    distribution  in  the   Williamson 
County  district. 

(b)  Sangamon,    Macoupin,    Christian,    Logan,    and    Macon 
Counties.    The  Springfield  district,  extending  into  several  adjoin- 
ing counties,  has  long  been  one  of  the  most  important.     Sangamon 
produced  more  than  5,000,000  tons  in  1907.      The  coal  of  the  dis- 
trict is  commonly  known  as   No.  5,    though  recent  work  tends  to 
confirm  the  suggestion  that  there  are  probably  two  distinct  beds 
mined  in  this  district, -No  5,  in  the  area  north  of  Chatham,  and  in 
No.  6  south  of  that  town.     The  average  thickness  is  a  little  less 
than  6  feet  at  Springfield,  about  4.5  feet  at  Decatur  and  from  6  to 
8  feet  in  Macoupin  County. 

(c)  St.  Clair,  Madison,  Clinton,  and  Randolph  Counties.    St. 
Clair  County  produced  more   than   4,500,000   tons  in  1907.     This 
district,  known  as  the  Bellville  district,  is  not  sharply  set  off  from 
its  neighbors  since  the  same  coal  bed  is  mined  under  similar  con- 
ditions in  adjoining  counties.      It  is  the  Blue  Band  seam  and  has 
a  thickness  of  from  5  to  7  feet  over  much  of  the  area.     The  seam 
is  reached  by  shafts  from  100  to  300  feet  deep. 


*  The  Coal  Resources  of  Illinois,   by  Prank  W.  DeWolf ,  Amer.  Inst.  of  Mining  Engineers, 
October,  1908. 


FUEL  TESTS  WITH  ILLINOIS   COAL  5 

(d)  Vermilion  County.     During  1907  Vermilion  County  pro- 
duced nearly  3,000,000  tons.     It  has  long  been  an  important  area, 
shipping  principally  to  the  Chicago  market.     There  are  three  per- 
sistent seams,  two  of  which   are  worked.      The   top  or  Danville, 
No.  7,  appears  west  of   Vermilion   river   and   is  mined  along  the 
outcrop  and  by  shafts  from  75  to  200  feet  deep.     The  other,  known 
as  the  Grape  Creek  coal,  No.  6,  lies  from  20  to  80  feet  below  the 
Danville  and  is  the  more  important  of  the  two. 

(e)  Saline  County.      Saline  County   is  one  of  the  newest  and 
most  rapidly  growing   producers.      In   1907  its  output  was  about 
2,1*25,000  tons,  a  gain  of  125  per  cent  over  1906.      There  are  two 
seams,  No.  7  and  No.    5,    underlying   the   northern  two-thirds  of 
this  county  and  much  of  Gallatin  on  the  east,  each  approximately 
5  feet  thick  and  lying  90  to  150  feet  apart  vertically. 

(/)  Fulton  and  Peoria  Counties.  Fulton  County  produced 
more  than  2,000,000  tons  in  1907  and  Peoria  about  half  as  much. 
Here  the  principal  seam,  called  No.  5,  is  from  4  to  4.5  feet  thick. 
Shafts  reach  the  coal  at  from  75  to  150  feet.  In  all,  seven  beds 
are  present. 

(g)  La  Salle,  Bureau  and  Grundy  Counties.  The  La  Salle 
district  includes  three  principal  counties  and  produces  more  than 
5,000,000  tons  yearly.  The  largest  production  is  by  long- wall 
mining  from  seam  No.  2,  or  the  Third  Vein.  The  coal  averages 
3  feet  thick  and  is  of  good  quality.  About  140  feet  above  it,  lies 
seam  No.  5.  It  is  about  4  feet  thick.  About  40  feet  above  No.  5 
is  seam  No.  7.  This  is  extensively  mined  by  room-and- pillar 
methods. 

2.  The  samples  tested  were  procured  from  5  of  the  7  districts 
described  in  the  preceding  paragraph.  They  were  furnished  by  the 
several  coal  mining  companies  of  the  state  free  of  cost,  and  were 
shipped  to  the  fuel  testing  laboratory  under  the  supervision  of  an 
expert  inspector  whose  chief  care  was  to  secure  a  sample  for  test- 
ing which  fairly  represented  the  normal  product  of  the  mine.  The 
cars  were  numbered  consecutively  in  the  order  of  shipment,  and 
this  number  has  been  retained  as  the  laboratory  designation  of 
the  sample.  When  two  or  more  car  lots  consisting  of  different 
grades,  such  as  lump,  nut,  etc.,  were  shipped  from  the  same  mine, 
each  lot  was  designated  by  a  letter.  For  example,  Illinois  11A 
is  screened  coal,  11B  run-of-mine  and  11C  No.  5  washed  coal,  all 
from  the  same  mine. 

A  complete  list  of  the  car-load  samples  of  Illinois  coal  re- 
ceived and  tested  is  given  in  Table  1.  In  this  table  the  location 


ILLINOIS   ENGINEERING   EXPERIMENT    STATION 


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FUEL  TESTS   WITH  ILLINOIS   COAL 


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FUEL  TESTS  WITH  ILLINOIS   COAL  9 

of  the  mine,  the  geological  bed  or  seam  and  the  name  of  the  mine 
or  its  depth  are  given.  Referring  to  the  table  it  will  be  seen  that 
fifty-three  car  samples  from  thirty-three  different  mines  were 
tested,  and  that  the  mines  are  distributed  throughout  twelve  of 
the  principal  coal  mining  counties  of  the  State.  The  location 
of  each  mine  is  plotted  on  the  map,  Fig  1. 

A  comparison  of  the  coal  output  of  the  several  localities  de- 
signated in  paragraph  2,  with  the  number  of  mines  submitting 
samples,  shows  that  the  coal  tested  is  fairly  representative  and 
while  it  is  true  that  two  comparatively  important  coal  producing 
localities  are  not  included,  the  results  of  tests  should  be  accepted 
as  characteristic  of  Illinois  coal  in  general. 

3.  The  plan  of  the  tests  as  adopted  by  the  United  States  Geo- 
logical Survey  included  a  complete  chemical  analysis  of  samples 
submitted,  an  investigation  of  the  advantages  of  washing,  an  in- 
vestigation of  the  coking  qualities  of  the  coal,  and  a  series  of  boiler 
and  gas  producer  trials.  In  carrying  out  this  plan  each  sample 
was  tested  under  conditions  as  nearly  identical  as  possible,  and 
every  effort  was  made  to  secure  results  which  would  admit  of  di- 
rect comparison. 


IV  CHEMICAL  PROPERTIES  OF  THE  COALS  TESTED 

To  determine  the  chemical  properties  of  the  coals  tested, 
samples  were  taken  both  from  the  working  face  of  the  mine  and 
from  each  car-load  shipped. 

4.  The  mine  samples  were  obtained  as  follows:  After  a  gen- 
eral inspection  of  the  mine  to  determine  the  variations  of  coal  in 
thickness  and  in  quality,  two  representative  points  were  selected  in 
opposite  parts  of  the  mine.  The  face  of  the  coal  at  these  places 
was  cleaned  in  order  to  remove  any  weathered  coal  or  powder 
smoke,  and  a  cut  made  across  the  face  of  the  coal  from  roof  to 
floor,  including  all  the  benches  mined  and  such  impurities  as  were 
not  removed  in  ordinary  work.  The  coal  obtained,  amounting  to 
25  or  30  pounds,  was  pulverized  and  quartered  down  according  to 
generally  accepted  rules,  and  the  sample  placed  in  an  air-tight 
iron  can.  This  was  mailed  to  the  chemical  laboratory  where  it 
was  received  and  analyzed  within  two  or  three  days. 


10  ILLINOIS    ENGINEERING    EXPERIMENT    STATION 

5.  The  car  samples  were  obtained  during  the  process  of  unload- 
ing at  the  testing  plant.      A  quantity  never  less  than  200  pounds 
and  often  as  great  as  600  pounds   was  collected,  a  shovelful  at  a 
time  from  every  part  of  the  car.    This  was  thoroughly  crushed  and 
quartered  down  until  25  or  30   pounds  remained ,  placed  in  an  air- 
tight can  and  immediately   shipped   to   the   chemical  laboratory. 
Here  the  sample  was  pulverized  and  again  quartered  until  a  con- 
venient amount  for  analysis  was  obtained . 

6.  The  chemical    work  included  calorific  determinations,  and 
ultimate  and  proximate  analyses.     The  calorific  value  was  deter- 
mined in  duplicate  for  each  car  sample.     A  determination  was  also 
made  for  one  of  the  two  mine  samples  corresponding  to  each  car- 
load.    An  ultimate  analysis  was  made  in  duplicate  on  each  car 
sample.     The  approximate  analysis  and  the  determination  of  sul- 
phur were  made  for  practically  every  sample  that  came  into  the 
laboratory,  and  were  made  in  duplicate  for  all  car  samples. 

7.  The  results  of  the   chemical   analyses  are  given  in  Tables  2 
and  3,  (p.  12,  et  seq.)     Column  1  gives  the  laboratory  number,  Col- 
umn 2  the  U.  S.  G.  S.  number,  Column  3,  the  coal  bed  or  seam  and 
Column  4,  the  location  from  which  the  sample  was  taken.    Column 
5  gives  the  designation  of  the  sample.    The  proximate  analysis  is 
given  in  Columns  6  to  14.     These  results  are  given  both  for  air- 
dry  coal  (Columns  7  to  10)  and  for  pure  coal  (Columns  12  to  14). 
The  calorific  value  is  given  in  terms  of  dry  coal  in  Column  11  and 
in  terms  of  pure  coal  in  Column  15.     Referring  to  the  latter  it  will 
be  seen  that  the  maximum  value  is  14900  and  the  minimum  13900, 
a  range  of  about  6.7  per   cent.      The    average,  however,  is  14319 
and  but  few  of  the  recorded  values   vary  from  this  by  an  amount 
greater  than  two  per  cent.     The  ultimate  analysis  is  given  in  Col- 
umns 16  to  21.     For  convenience  in  comparing  the  results  this  is 
put  in  terms  of  dry  coal.     Columns  22,  23  and  24  have  been  calcu- 
lated from  the  ultimate  and  proximate  analyses.     The  combustible 
volatile  is  equal  to  the  difference   between  the  total  volatile  (Col- 
umn 12)  and  the  inert  volatile  (Column  23).      The  inert  volatile  is 
equal  to  100  minus  the   total  carbon,  the  ash,  the  water,  the  sul- 
phur and  the  available  hydrogen  all  divided  by  100  minus  the  ash 
and  water.     The  ratio  of   the   volatile  carbon  to  the  total  carbon 
(Column  24)  is  equal  to  total  carbon  as  shown  by  the  ultimate  anal- 
ysis minus  the  fixed  carbon  as   shown  by  the  proximate  analysis 
divided  by  the  total  carbon. 


FUEL   TESTS   WITH   ILLINOIS   COAL 


11 


The  values  included  in  Columns  22,  23  and  24  have  been  cal- 
culated in  order  to  make  possible  a  classification  based  on  the 
ratio  of  volatile  carbon  to  total  carbon.  This  is  the  classification 
suggested  by  Professor  S.  W.  Parr,  and,  in  brief,  is  as  follows.* 

VC 
Anthracite  Proper Ratio  -^-  below  4% 

VC 
Anthracite      Semi- Anthracite Ratio  -~-  between  4%  and  8% 

VC 

Semi-Bituminous Ratio  -^  between  10%  and  15% 

VC 
A  \  Ratio  -^  from  20%  to  32% 

(  Inert  Volatile  from  5%  to  10% 


COAL 


Bituminous  Proper 


Black  Lignites 
Brown  Lignites 


VC 

B  j  Ratio  -~  from  20%  to  27% 

Inert  Volatile  from  10%  to  16% 

VC 

Ratio  -^  from  32%  to  44% 

Inert  Volatile  from  5%  to  10% 

VC 
D  _j  Ratio  -^  from  27%  to  44% 

Inert  Volatile  from  10%  to  16% 


Ratio        from  27%  up 

Inert  Volatile  from  16%  to  20% 

VC* 

Ratio  -^  from  27%  up 

Inert  Volatile  from  20%  to  30% 


It  will  be  seen  that  in  this  system  of  classification  all  samples 
of  Illinois  coal  tested  fall  in  one  of  two  divisions,  bituminous  B 
and  bituminous  D.  In  Table  IV  (p.  18)  they  have  been  arranged  in 
the  order  of  their  volatile-carbon  total-carbon  ratio.  Referring  to 

VC 

Column  2  of  this  table  the  minimum  value  of  the  ratio  —    is  20.9 

o 

and  the  maximum  33.4.    The  inert  volatile  calculated  on  the  pure 
coal  basis  varies  from  12.5  to  16.3. 

The  classification  of  the  several  coal  beds  or  seams  of  the 
state  as  used  in  the  state  coal  reports  has  often  been  questioned; 
nevertheless  it  is  of  interest  to  note  that  in  so  far  as  the  present 
tests  can  be  taken  as  an  index,  seam  No.  7  falls  in  Class  B,  and 
seam  No.  6  falls  in  Class  D.  Furthermore  if,  as  has  been  pointed 
out,  (paragraph  2,  section  b,  Chapter  II)  certain  of  the  Blue  Band 


Composition  and  Character  of  Illinois  Coals,  by  S.  W.  Parr,  Illinois  State  Geological  Sur- 
vey, Bulletin  No.  3. 


12 


ILLINOIS   ENGINEERING   EXPERIMENT    STATION 

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FUEL  TESTS  WITH  ILLINOIS  COAL 


15 


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16  ILLINOIS   ENGINEERING   EXPERIMENT    STATION 


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FUEL   TESTS   WITH  ILLINOIS   COAL 


17 


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ILLINOIS   ENGINEERING   EXPERIMENT   STATION 


coals  of  Sangamon  County  in  reality  belong  to  Seam  6  instead  of 
5,  Class  B  would  also  include  all  coals  tested  from  seam  No.  5. 
The  single  sample  from  Seam  No.  2,  (U.  S.  G.  S.  18)  falls  in  Class 
D,  well  up  towards  the  lignites. 


TABLE  IV 

CLASSIFICATION  OF  ILLINOIS  COAL  ON  THE  BASIS  OF  THE 
VOLATILE-CARBON  AND  TOTAL-CARBON  RATIO 


U.  S.  G.  S. 
Number 

Ratio  of 
Volatile 
Carbon 
to  Total 
Carbon 

Inert 
Volatile 
(Pure  Coal 
Basis) 

Class 

Coal 
Bed   or 
Seam 

1 

2 

3 

4 

5 

28 

20.90 

12.50 

B 

» 

6 

22.20 

13.35 

B 

5 

3 

22.50 

12.20 

B 

16 

22.90 

12.50 

B 

7 

19 

23.00 

12.30 

B 

7 

12 

23.63 

12.20 

B 

7 

21 

23.70 

16.30 

B 

6 

13 

24.70 

13.00 

B 

11 

24.77 

12,00 

B 

7 

34 

25.40 

12.90 

B 

5 

10 

26.20 

13.30 

B 

7 

24 

26.90    • 

12.50 

D 

6 

20 

26.90 

13.60 

D 

6 

29 

27.13 

13.50 

D 

5 

31 

27.60 

13.10 

D 

6 

4 

28.30 

12.36 

D 

6 

9 

29.00 

13.00 

D 

6 

22 

29,20 

12-70 

D 

6 

23 

29.30 

13.30 

D 

6 

25 

29.20 

13.40 

D 

6 

15 

29  50 

13.20 

D 

6 

26 

29  80 

12.50 

D 

5 

27 

29.80 

13.50 

D 

6 

8 

30.30 

12.70 

D 

6 

14 

30.60 

12-40 

D 

5 

30 

31.00 

14.00 

D 

6 

33 

31.00 

12.80 

D 

7 

18 

31.80 

12.70 

D 

2 

7 

32.80 

12.95 

D 

6 

1  &  2 

33.40 

12.95 

D 

6 

V    WASHING  TESTS 

8.  The  equipment  for  the  washing  tests  of  Illinois  coal  consists 
of  one  modified  Stewart  jig  and  one  jig  especially  designed  for 
the  laboratory,  a  Cornish  tooth-roll  crusher,  an  adjustable-mesh 
bumping  screen,  and  bins  of  suitable  capacity  for  storing  the  coal. 
The  Stewart  jig,  shown  in  Fig.  2,  provides  for  the  washing  of 
coal  not  exceeding  1J  inches  in  diameter.  The  special  jig  may  be 
used  for  larger  sizes.  It  is  of  the  center- plunger  type,  that  is, 
the  plunger  is  directly  beneath  the  screen.  Its  upward  stroke 
causes  the  pulsation,  and  its  downward  stroke,  by  an  arrange- 
ment of  valves  at  the  side  of  the  jig  body,  admits  the  water  sup- 


FUEL  TESTS  WITH  ILLINOIS   COAL  19 

ply.  The  screen  is  4  feet  wide  by  5  feet  long  and  is  constructed 
of  No.  10  wire  set  1-16  inch  apart.  The  length  of  stroke  and  the 
depth  of  the  coal  bed  are  adjustable. 


FIG.  2    STEWART  JIG  (PROF.  PAPER  48,  p.  1460) 

9.  The  tests  involved  the  weighing  of  the  raw  and  washed 
coal,  and  the  refuse.   Samples  of  the  coal  were  collected  before  and 
after  it  was  fed  to  the  jig.       These  were  sent  to  the  chemical  lab- 
oratory for  analysis.     Altogether  31  tests  were  made  on  24  kinds 
of  coal. 

10.  The  results  of  the  tests  are  given  in  Table  5.    Column  1  of 
this  table  is  the  U.  S.  G.  S.  coal  number,   Column  2  the  jig  used 


20 


ILLINOIS   ENGINEERING    EXPERIMENT   STATION 


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Egg  crushed  to  2  in  . 
Lump  crushed  to  2  in. 
Lump  &  Egg(crus:rud  to  2  in. 

Lump  crushed  to  2  in 
Screenings  crushed  to  2  in. 
Lump  crushed  to  2  in. 

Nut  &  Slack  crushed  to  2  in. 
Lump  crushed  to  2  in. 
Screenings  crushed  to  2  in. 

Nut  crushed  to  2  in. 
Run  of  Mine  crushed  to  2  in. 

Lump  crushed  to  2  in. 
Screenings  crushed  to  2  in. 

Nut  crushed  to  2%  in. 
Nut  crushe  i  to  1  in. 
Screenings  crushed  to  1  in. 

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FUEL   TESTS   WITH   ILLINOIS   COAL 


21 


and  Column  3  the  size  of  the  coal.  The  proximate  analysis  of  the 
raw  and  washed  coal  is  given  in  Columns  4  to  11.  The  weight  of 
raw  coal  tested  is  given  in  Column  12  and  the  washed  coal  pro- 
duced in  Column  13.  Column  14  gives  the  refuse  expressed  in  per 
cent  of  raw  coal  fed  to  the  jig. 

11.  The  improvement  in  quality  of  the  coal  effected  by  wash- 
ing is  well  shown  in  Columns  4  to  11.  For  example  the  percent 
of  ash  content  is,  in  every  case,  decreased  by  washing.  This  is 
shown  graphically  in  Fig.  3.  In  this  figure  the  per  cent  of  ash 
in  the  washed  coal  is  plotted  against  per  cent  of  ash  in  the  raw 
coal.  The  average  line  shows  that  by  resorting  to  the  process  of 
washing,  it  is  possible  to  reduce  the  ash  content  from  22  per 
cent  to  8.7  per  cent  and  from  10  per  cent  to  6.9  per  cent.  Ex- 
pressed in  per  cent  the  amount  of  reduction  is  as  follows: 

When  raw  coal  contains  8%  ash,  the  reduction  is  20%. 
When  raw  coal  contains  12$  ash,  the  reduction  is  30%. 
When  raw  coal  contains  16  %  ash,  the  reduction  is  43%. 
When  raw  coal  contains  20 %  ash,  the  reduction  is  53%. 


210 

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4          6          8        10        12        14        16        18        20 

Per  Cent  of  Ash  in  Raw  Coal 
FIG.  3    REDUCTION  OF  ASH  DUE  TO  WASHING 


22 


22 


ILLINOIS   ENGINEERING    EXPERIMENT    STATION 


In  a  similar  way  the  reduction  in  sulphur  due  to  washing  is 
shown  in  Fig.  4.     Referring  to  this  figure  it  will  be  seen  that: 

When  raw  coal  contains  2%  sulphur,  the  reduction  is  13%. 
When  raw  coal  contains  3%  sulphur,  the  reduction  is  17%. 
When  raw  coal  contains  4%  sulphur,  the  reduction  is  22%. 
When  raw  coal  contains  5%  sulphur,  the  reduction  is  28%. 


73   4 

o 
0 


12345 
Per  Cent  of  Sulphur  in  Raw  Coal 

FIG.  4    REDUCTION  OF  SULPHUR  DUE  TO  WASHING 

In  bringing  about  this  improvement  in  the  quality  of  coal  by 
washing,  much  good  coal  which  can  not  be  recovered  is  carried 
off  with  the  refuse  from  the  jig.  For  example,  the  tests  show 
that,  based  on  the  average  of  all  tests,  the  refuse  amounts  to  16.8 
per  cent  of  the  raw  coal.  The  ash  in  the  raw  coal  is  12.6  per  cent, 
but  in  the  washed  coal  this  is  reduced  to  8.34  per  cent,  therefore 
12.6-  88.2X8.34  or  5.7  per  cent  is  the  ash  content  in  the  refuse. 
It  appears,  then,  that  the  material  thus  discharged  is  made  up  of 
about  |  pure  coal  and  i  ash. 


FUEL  TESTS  WITH  ILLINOIS  COAL  23 

VI    COKING  TESTS 

12.  The  ovens  in  which  tests  of  the  coking  qualities  of  the 
coal  were  made  are  of  the  regular  beehive  pattern.     Originally 
they  were  arranged  in  a  battery  of  three,    two  of  standard  size, 
12  feet  in  diameter,  by  7  feet  high,  and  the  third  12  feet  in  diam- 
eter by  6  feet  4  inches  high;  later,  however,  one  of  the  standard 
ovens  was  removed.     Since  the  two  remaining  ovens  may  be  con- 
sidered as  end  ovens,  that  is,  those  placed  at  the  ends  of  the  bat- 
tery, the  results  obtained  are  directly  comparable. 

13.  The   tests. — To   prepare   the  coal  for  test  it  was  finely 
crushed  in  a  Williams  mill.     It  was  then  placed  on  the  larry  and 
delivered  to  the  oven.     The  larry  used  when  the  work  was  begun 
had  a  capacity  less  than  one  ton.  This  necessitated  the  filling  and 
emptying  of  the  larry  six  or  eight  times  before  the  charge  was 
complete.     Each  portion  thus  had  time  to  emit  a  large  amount  of 
gas  and  often  to  burst  into  flames  before  the  next  portion  of  the 
charge  was  added.       This  resulted  in  much  injurious  cross  lami- 
nation of  the  coke  in  many  of  the  earlier  tests.    Afterwards  when 
a  larger  larry  was  installed  and  the  time  of  charging  reduced 
from  one  hour  to  less  than  seven  minutes  the  laminations  and 
cross-breakage  disappeared. 

Directly  after  drawing  the  charge  the  ovens  were  closed  for 
a  period  of  one  or  two  hours  during  which  time  they  were  allowed 
to  gather  heat  for  the  next  charge. 

A  sample  of  coal  was  taken  at  regular  intervals  as-the  charge 
was  emptied  into  the  larry.  The  total  weight  collected  was  40  or 
50  pounds.  A  sample  of  coke  was  taken  from  5  different  parts  of 
the  oven,  one  piece  2  feet  from  the  oven  floor,  one  2  feet  from 
each  side  on  a  line  drawn  from  the  center  of  the  oven,  one  from 
the  center  of  the  oven,  and  one  2  feet  from  the  back  wall:  The 
separate  pieces  of  coke  extended  the  whole  height  of  the  charge 
and  were  as  nearly  uniform  in  size  as  possible. 

14.  The  results  of  the  tests  are  given  in  Table  6.    Column  1  of 
this  table  is  the  test  number,  Column  2  the  U.  S.  G.  S.  number, 
and  Column  3  the  size  as  shipped  to  the  laboratory.      The  proxi- 
mate analysis  of  the  coal  and  coke  produced  from  it  is  given  in 
Columns  4  to  13.      Column  14  gives  the  weight  of  coal  in  the 
charge.     The  coke  produced  in  per  cent  of  the  weight  of  the  coal 
charged  is  given  in  Column  15,  and  the  per  cent  of  breeze  in  Col- 
umn  16.     The  total  yield  as  given  in  Column  17  is  the  sum  of  the 
coke  aod  breeze  produced.     A  brief  description  of  the  physical 


24  ILLINOIS   ENGINEERING   EXPERIMENT    STATION 


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FUEL   TESTS   WITH   ILLINOIS   COAL 


25 


.fitctfi 


26  ILLINOIS   ENGINEERING   EXPERIMENT   STATION 

properties  of  the  coke  produced  is  given  in  Column  18. 

In  reviewing  the  results  of  the  tests  as  set  forth  in  Table  6, 
it  should  be  remembered  that  the  necessary  routine  work  involved 
in  the  testing  of  so  many  coals  made  it  possible  to  make  but  few 
tests  on  each  coal.  The  data  presented,  therefore,  show  the 
results  obtained  under  conditions  which  of  necessity  had  to  be 
controlled  by  observations  made  from  time  to  time  as  the  coking 
proceeded,  a  procedure  which  tended  to  make  the  conditions  of 
operations  by  no  means  ideal. 

Of  the  37  tests  made  with  Illinois  coal  9  resulted  in  the  pro- 
duction of  comparatively  good  coke  and  14  in  the  production  of 
a  poor  grade  of  coke.  The  remaining  14  samples  apparently  proved 
to  be  non-coking  coals.  Referring  to  the  approximate  analyses 
of  the  coke  produced  it  will  be  seen  that  in  a  number  of  cases  the 
quality  of  the  coke  is  by  no  means  inferior,  though  in  all  cases  the 
ash  and  sulphur  content  is  slightly  greater  than  is  desirable. 
Seven  samples  (11D  washed,  13,  13  washed,  16,  22B  washed,  and 
29  washed)  were  successfully  used  in  a  foundry  cupola. 


VII    STEAMING  TESTS 

15.  The  apparatus  comprising  the  plant  for  steam-ing  tests  con- 
sisted of  two  standard  Heine  water- tube  boilers  equipped  with 
hand-fired  furnaces  and  an  Allis-Chalmers  Corliss  engine  oper- 
ating a  200  kilowatt  Bullock  generator.  A  plan  and  elevation  of 
one  of  the  boilers  and  its  setting  are  shown  in  Fig.  5  and  the 
general  appearance  as  set  up  in  the  laboratory  in  Fig.  6. 

The  equipment  used  for  testing  the  boilers  provided  conveni- 
ent and  accurate  means  for  measuring  the  coal  and  water  and  for 
making  all  observations  of  pressure,  temperature,  etc.,  specified 
in  the  boiler  testing  code  of  the  American  Society  of  Mechanical 
Engineers.  It  consisted  principally  of  water-weighing  tanks, 
scales,  charging  cars,  sampling  cans,  apparatus  for  analyzing  flue 
gases,  pressure  gages,  calorimeters,  thermometers  and  draft 
gages*. 


*This  apparatus  is  described  in  detail  in"Professional  Paper  No.  48"  United  States  Geolog- 
ical Survey. 


FUEL   TESTS    WITH   ILLINOIS   COAL 


27 


28 


ILLINOIS   ENGINEERING   EXPERIMENT   STATION 


i 


FUEL   TESTS   WITH   ILLINOIS   COAL  29 

The  principal  dimensions  of  the  boiler  and  furnace  are  as 
follows: — 

Length  of  drum feet 21.58 

Inside  diameter  of  drum inches 42. 

Number  of  tubes,  11  tubes  high  by  11  tubes  wide 116 

Outside  diameter  of  tubes inches 3.5 

Width  of  furnace ' feet 6.16 

Length  of  furnace feet 6.58 

Mean  height  of  furnace inches 26.00 

Grate  area square  feet. . .  40.55 

Ratio  of  grate  area  to  air  space 40. 17 

Water-heating  surface  in  tubes square  feet . .  .1897 

Water-heating  surface  in  water  legs square  feet ...  91 

Water-heating  surface  in  shell square  feet. . .  43 

Total  water-heating  surface square  feet . .  .2031 

Ratio  of  heating  surface  to  grate  area 50. 1 

16.  The  Tests.      Since  the  establishment  of  the  fuel  testing 
division  of  the  United  States   Geological  Survey,  more  than  500 
boiler  trials  have  been  made,   and  of  these,  112  involved  the  use 
of  Illinois  coal.      Tests  were  made  with  each  of  the  34  samples 
submitted,  the  coal  being  used  either  in  its  natural  state  or  in  the 
form  of  briquets,  or  both.      A  number  of  tests  were  also  made 
with  washed  coal. 

A  summary  of  the  principal  observed  and  derived  results  of 
tests  with  Illinois  coals  is  given  in  Tables  7  and  8.  In  these  tables 
only  such  values  as  have  a  direct  relation  to  boiler  performance 
are  included;  additional  data,  however,  may  be  found  in  the 
reports  published  by  the  United  States  Geological  Survey.* 

17.  The  description  of  the  coal  tested  given  in  Table  7,  Column  1 , 
of  this  table  is  the  serial  number  of  the  test  and  is  useful  as  a  means 
of  identification.     Tlie  number  describing  the  location  from  which 
the  sample  was  taken,  is  given  in  Column  2  and  the  number  of 
the  coal  bed  or  seam,  in  Column  3.      The  size  of  the  coal  is  given 


*  Bulletin  No.  332  and  Professional  Paper  No-  48. 


30  ILLINOIS   ENGINEERING   EXPERIMENT    STATION 

in  Columns  4  to  9.  The  size  as  shipped  (Column  9)  was  not  always 
the  same  as  that  used  in  the  tests  since  in  some  cases  it  was 
crushed  or  screened  after  it  was  received.  The  actual  size  as 
determined  from  samples  taken  during  each  test  is  given  in  pre- 
cise terms  in  Columns  5,  6,  7  and  8,  and  the  average  diameter 
calculated  from  these  data  is  given  in  Column  9.  The  proximate 
analyses  (Columns  10  to  14)  were  made  from  samples  collected 
for  each  test  and  are  given  in  the  tables  in  terms  of  coal  as  fired. 
Calorific  values  were  not  determined  for  every  test.  The  values 
given  (Column  15)  were  calculated  from  the  proximate  analysis 
and  the  calorific  value  determined  from  the  car  sample,  on  the 
assumption  that  the  B.  t.  u.  per  pound  of  pure  coal  (ash  and  mois- 
ture free)  is  the  same  for  each  car  load  shipped  to  the  testing 
plant. 

18.  The  performance  of  the  boiler  and  furnace  is  given  in  Table 
8.  Column  17  gives  the  average  boiler  pressure  in  pounds  per 
square  inch.  The  standard  pressure  was  75  but  it  will  be  seen 
that  the  values  given  vary  from  68  to  81.  The  draft  above  the 
fire  (Column  18)  was  measured  in  inches  of  water.  In  some  tests 
it  was  as  great  as  .3  inch;  the  average  however,  is  a  little  less 
than  .2  inch. 

The  furnace  temperature  (Column  19)  was  observed  with  a 
Wanner  optical  pyrometer.  The  results  .given  are  averages  of  a 
number  of  readings  which  varied  over  a  considerable  range 
throughout  the  test.  The  lowest  temperature  recorded  is  1887° 
and  the  highest  2829°  F. 

The  rate  of  combustion  in  terms  of  dry  coal  fired  per  hour, 
per  square  foot  of  grate  surface  (Column  20)  is,  for  most  tests, 
about  25  pounds.  This  rate,  it  will  be  seen,  is  sufficient  to  evap- 
orate, in  most  cases  5i  pounds  of  water  from  and  at  212°  F.  per 
square  foot  of  heating  surface  per  hour  (Column  21)  or  100  per 
cent  of  the  rated  horse -power  (Column  22). 

The  evaporative  efficiency  is  given  in  Columns  23,  24  and  25. 
In  Columns  23  and  24  the  equivalent  evaporation  per  pound  of 
coal  as  fired  and  per  pound  of  dry  coal,  respectively,  is  given. 
The  values  given  in  Column  25  represent  the  over-all  efficiency, 
that  is,  the  ratio  of  the  heat  absorbed  by  the  water  in  the  boiler 
to  the  potential  heat  in  the  coal  fed  to  the  furnace.  It  is  evident, 
therefore,  that  this  is  the  best  measure  of  the  value  of  any  parti- 
cular fuel  for  steam  generation  since  it  expresses  the  exact  pro- 
portion of  heat  purchased  in  the  form  of  coal  which  can  be  con- 
verted into  useful  energy  in  the  form  of  steam.  Referring  to  the 


FUEL  TESTS  WITH  ILLINOIS   COAL 
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32 


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34 


ILLINOIS   ENGINEERING   EXPERIMENT    STATION 


TABLE  8    STEAMING  TESTS— PERFORMANCE  OF  BOILER 
AND   FURNACE 


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95.9 

5.99         6.91 

55.14 

122 

72                .30 

20-08         2.19 

61.4 

5.44          6.08 

58.71 

5.74 

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73 

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19.92 

3.19 

89.6 

6.70          8-02 

60.84 

4.36 

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81 

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2.97 

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6.65 

7.44 

61.39 

4.70 

143 

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18.74 

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6.46 

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62.01 

4.85 

146 

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7.40 

64.45 

4.72 

516 

79 

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31.99 

3.70 

103.7 

4.95 

5.79 

54.38 

6.03 

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83.5 

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28.82 

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49.86 

5.61 

102 

78 

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38.36 

3.62 

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5.58 

6.39 

51.41 

5.46 

103 

81                .27 

22J8 

26.53 

3.61 

101.1 

5.94 

6.81 

52.59 

5.13 

104 

80               .  19 

2155 

23.22 

3.01 

84.4 

5.70 

6.50 

50.  2S 

5.37 

105 

78               .25 

2220 

30.26 

4.08 

114.3 

5.93 

6.75 

51.92 

5.17 

113 

75                .20 

25.60 

3.05 

85.6 

5.68 

6.66 

49.67 

5.24 

121 

75                .19 

26.60 

3.57 

100.0 

6.69 

7.49 

58.15 

4.66 

492 

76.5            .16 

3.50 

98.2 

6^65 

7.79 

62.50 

4.48 

107 

76                .32 

2229 

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89.9 

6.76 

7.65 

59.44 

4.56 

108 

76                .21 

22.24 

3.13 

87.6 

6.39 

7.04 

53.60 

4.96 

109 

78                .29 

21.46          2.96 

83.0 

6.90 

7.70 

60.10 

4.53 

110 

75               .26 

20.66     !     2.48 

69.6 

6.08 

6.71 

50.12 

5.20 

114 

75                .21 

24.23 

3.52 

98.7 

7.16 

8.11 

57.82 

4.30 

137 

74               .16 

20.98 

3.17 

88.8 

7.76 

8.42 

64.51 

4.14 

138 

74               .18 

2376 

19.94 

2.97 

83.4 

7.68 

8.32 

66.08 

4.20 

139 

77               .18 

2435 

19.70 

3.06 

85.9 

8.02 

8.67 

68.33 

4.03 

141 

79                .15 

18.81 

3.11 

87.3 

7.66 

8  29 

64.02 

4  21 

111 

73.5     !        .28 

24.35 

2.93 

82.0 

6.15 

6.70 

51.18 

5.21 

112 

80                .27 

22.36 

2.90 

81.2 

6.59 

7.23 

54.65 

4.83 

115 

76                .26 

22.89 

3.42 

95.9 

6.83 

7.49 

58.71 

4.66 

116 

76 

.22 

24.19 

3.61 

101-3 

6.94 

7.48 

55.85 

4.67 

117 

75.5 

.20 

23.80 

3.42 

95.8 

6.71 

7.19 

55.38 

4.85 

118 

77                .16 

23.16 

3.32 

93.1 

6.74 

7.19 

54.26 

4  85 

119 

75                .  25 

25.70 

3.75 

105.0 

.84 

7.31 

53.97 

4.78 

120 

72 

.23 

25-41 

3.55 

99.5 

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7.79 

56.27 

4.48 

312 

71 

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2400 

19-38 

3.40 

95.4 

.96 

8.80 

63.60 

127 

73               .19 

21.49 

3  35 

94.0 

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7.81 

63.04 

4.50 

128 

75                -19 

21.45 

3.51 

98.3 

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8.19 

65.07 

4.26 

131 

74                .19 

20-87 

2.91 

81.50 

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7.74 

64.08 

4.49 

133 

81                .22 

22-91 

3.15 

88-2 

,00 

7.67 

62.51 

4.55 

135 

74 

,18 

23.09          3.62 

101.3 

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8.75 

64.48 

3.99 

136 

75 

.21 

20.77 

2.91 

81.5 

7.00 

7.81 

63.56 

4.47 

463 

81 

.11 

2490 

18-67 

3.20 

89.7 

7.98 

8.58 

64.44 

4.07 

132 

76 

.13 

22.06 

3.37 

94.5 

7.67 

8.52 

65.67 

4.10 

134 

78 

.18 

22.55 

3.39 

95.0 

7.58 

8.39 

63.96 

4.16 

144 

79 

.10 

20.42 

3.70 

103.8 

8.20 

9  .  08 

66.12 

3.84 

145 

75 

.13 

20.14 

3.38 

94.7 

8.37 

9.36 

67.93 

3.73 

123 

73 

.28 

23.60 

3.10 

87.0 

6.49 

7.34 

59.03 

4.76 

125 

74 

.20 

20.30 

3.08 

86.2 

6.62 

7.58 

60.37 

4.61 

130 

77 

.14 

21.63 

3.33 

93.3 

6.49 

7.71 

58.48 

4.53 

126 

69 

.18 

20.44 

3.11 

87.2 

6.86 

7.62 

62.62 

4,58 

FUEL  TESTS  WITH  ILLINOIS   COAL 


35 


TABLE  8    STEALING  TESTS— PERFORMANCE  OF  BOILER 
AND  FURNACE    (Continued) 


8 

s  «^  § 

Equivalent 

Test  No. 

Boiler  Pressure 
Ib.  per  sq.  in. 

Draft  above  Fire 
inches  of  Water 

mperature  of  Furna< 
Degrees  F. 

)ry  Coal  per  sq.  ft.  ol 
Grate  Surf  ace  per 
hour,  pounds 

niviilrnt.  Kv;i]iui'nt.i( 
Dm  and  at  2!2°F.  pei 
ft.  of  Heating  Surfa 
Per  Hour,  pounds 

Per  Cent  of  Rated 
orsepower  Develope 

Pounds  of 
Water  Evap- 
orated from 
and  at  21  2°  F 
Per  Pound 

Efficiency  of  Boiler 
ncluding  the  Grate 
Per  Cent 

s|J 
1 

•3? 

5f-> 
£ 

§| 

& 

i—  i 

&i 

w       o§ 

s° 

M 

3 

1 

16           17 

18                19             20 

21 

22 

23 

24 

25 

152 

75 

.13 

2439 

19.63 

3.36 

94.3 

7.57 

8.59 

63-30 

4.06 

150 

74 

.11 

.... 

19.63 

3.56 

99.8 

8.24 

9.08 

68.11 

3.85 

140 

75 

.18 

18.51 

2.86 

80.1 

-.60 

8.61 

64.20 

4.06 

147 

72 

.17 

19.53 

3.12 

87.4 

-.57 

8.91 

63.48 

3.92 

148 

73 

.19 

18.86 

2.99 

83.9 

-.06 

7.94 

59.02 

4.40 

149 

74 

.14 

2060 

17.83 

3.29 

92.2 

-.70 

9.23 

66.36 

160 

77 

.14 

2428 

18.47 

3.07 

86.1 

-.27 

8.33 

61.71 

4.'i9 

161 

77 

.20 

2080 

17.77 

3.12 

87.6 

-.62 

8.80 

65.82         3.97 

163 

78 

.17 

2227 

20.79 

3.57 

100.2 

7.50 

8.61 

63.63         4.06 

170 

79 

.16 

2039 

20.22 

3.10 

87.0 

-.42 

8.56 

64.29         4.08 

171 

77 

.17 

20.08 

3.23 

90.6 

-.79 

8.97 

67.06    I     3.89 

175 

74 

.09 

2470 

20.54 

3.73 

104.7 

8.13 

9.10 

67.50     :     3.84 

204 

72.5 

.11 

2447 

20.69 

3.50 

98.2 

8.54 

9.45 

69.93         3.70 

205 

.12 

2448 

20.38 

3.38 

94.9 

8.32 

9.27 

68.86         3.77 

420 

79.5 

.12 

.... 

19.95 

3.35 

93.9 

7.67 

8.40 

65.26    !    4.16 

423 

78.5 

.14 

.... 

16.94 

2.89 

81.0 

7.73 

8.53 

65.92     I     4.09 

424 

83.5 

.12 

18.67 

3.18 

89.1 

7.81 

8.53 

66.35 

4.09 

425 

81 

.14 

19.33 

3.32 

93.0 

7.87 

8.61 

66.73 

4.05 

421 

82 

.11 

19.46 

3.30 

92.5 

7.70 

8.48 

65.76 

4.12 

422 

78.5 

.12 



19,46 

3.39 

95.0 

7.88 

8.73 

67.03 

4.00 

292 

70.5 

.10 

2020 

15-49 

2.37 

66.3 

6.55 

7.66 

64.75 

4.56 

301 

69 

.30 

24.61 

3.54 

99.3 

6.71 

8.04 

62  08 

4.34 

302 

76 

.17 

2708 

25.69 

3.81 

106.7 

6.91         8.27 

63.65 

4.22 

315 

74.5 

.16 

2499 

20.05 

3.27 

91.6 

6.94         8.16 

65.97 

4.28 

316 

69 

.15 

2401 

20.05 

3.19 

89.3 

6.76 

7.96 

62.80 

4.39 

318 

69.5 

.04 

2508 

25.30 

4.11 

115.3 

6.73 

8.14 

63.04 

4.29 

324 

71.5 

.20 

2850 

23.08 

3.60 

100.9 

6.91         7.81 

65.67 

4.47 

325 

72 

.18 

2828 

22.61 

3.60 

101.0 

7.14         7.97 

64.81 

4.38 

328 

71 

.14 

2829 

26.73 

4.34 

121.8 

6.97 

8.14 

60.82 

4.29 

306 

67 

.13 

2402 

18.50 

3.01 

84.3 

6.97 

8.15 

66.93 

4.29 

317 

70.5 

.13 

2397 

19.63 

3.23 

90.4 

7.02         8.23 

62.12 

4.24 

321 

70.0 

.27 

23.75 

3.78 

106.0 

6.89     |     7.97 

59.22 

4.38 

322 

74.5 

.16 

24.54 

3.80 

106.6 

6.71         7.76 

57.66 

4.50 

335 

74.5 

.22 

2708 

20.49 

3.30 

92.6 

7.09         8.07 

63.68 

4.33 

336 

73.5 

.26 

21.48 

3.29 

92.3 

6.71         7.67 

58-68 

4.55 

337 

72 

.20 

23.63 

3.82 

107.0 

7.00         8.10 

62.71 

4.31 

338 

71.5 

.21 

21.36 

3.10 

87.0 

6.38     |     7.28 

56.16 

4.80 

339 

73 

.21 

23.63 

3.54 

99.1 

6.63     j     7.50 

60.25 

4.66 

341 

76 

.34 

20.91 

2.84 

79.7 

6.56         7.58 

60.85 

4  61 

342 

77 

.30 

2264 

23.02 

3.16 

88.6 

6.47 

7.67 

60.42 

4.55 

353 

78 

.18 

2360 

19.83 

3.14 

88.0 

6.66 

7.93 

64.73 

4.40 

354 

76 

.17 

2162 

19-26 

3.08 

86.4 

6.75 

8.02 

66.12 

4.36 

459 

80 

.15 

2601 

18.72 

3.13 

87.7 

7.75 

8.36 

64.29 

4.18 

457 

81 

.16 

2606 

19.85 

3-42 

95.9 

8.13 

8.64 

64.99 

4.04 

448 

79 

.17 

2862 

22.52 

3.88 

108.8 

8.21 

8.63 

64.50 

4.05 

452 

82.5 

.14 

2833 

21.97 

3.94 

110-5 

8.35 

8-98 

66.35 

3.89 

465 

75.5 

-15 

2665 

20.35 

3.62 

101.5 

7.65 

8.91 

65.58 

3.92 

460 

81.5 

.18 

2759 

21.38 

3.44 

96.3 

7.16 

8.05 

65.08 

4.34 

461 

80.5 

.18 

2816 

22.32 

3.72 

104.2 

7.31 

8.34 

63.28 

4.19 

466 

79.5 

.16 

2784 

22.32 

3.90 

109.2 

7.87 

8.74 

66.14 

3.99 

511 

79.5 

.19 

.... 

20.94 

3.59 

100.7 

7.76         8.60 

62.58 

4.06 

489 

74 

.14 

21.16 

3.49 

97.7 

7.06     !     8.25 

64.76 

4.23 

491 

82 

.20 



21.65 

3.56 

100.0 

7.35     i     8-24 

64.51 

4.24 

513 

82 

.10 

2465 

26.41 

3.23 

90.7 

5.43         6.13 

53.34 

5.69 

509 

82               .22 

21.50 

3.79 

106.2 

8.24         8.82 

62.53 

36  ILLINOIS   ENGINEERING   EXPERIMENT   STATION 

values  given,  it  will  be  seen  that  but  few  fall  below  55  per  cent  or 
above  65  per  cent,  the  maximum  and  minimum  efficiency  recorded 
being  68.11  and  49.64  respectively. 

In  reviewing  the  results  set  forth  in  Tables  7  and  8  it  should 
be  remembered  that  they  apply  only  to  the  performance  of  a 
hand-fired  water-tube  boiler  of  the  Heine  type  and  that  any  con- 
clusions which  may  be  drawn  are  thus  limited.  Had  it  been  pos- 
sible to  provide  a  furnace  especially  adapted  to  the  burning  of 
each  particular  coal,  the  relative  efficiency  as  established  by  the 
tests  might  have  been  slightly  different.  The  results  obtained, 
however,  may  be  accepted  as  fairly  indicative  of  the  value  of  the 
coals  tested.  With  this  in  view,  then,  it  will  be  of  more  than  ordi- 
nary interest  to  study  the  effect  of  the  physical  and  chemical  prop- 
erties of  the  fuel  upon  the  performance  of  the  boiler  and  furnace 
as  set  forth  in  the  tables. 

19.  Furnace  temperature.      It  will  be  seen  that  while  the 
results  do  not  show  any  exact  relation  between  efficiency,  furnace 
temperature  and  rate  of  combustion,   nevertheless  they  clearly 
indicate  that  as  the  rate  of  combustion  increases,  the  temperature 
increases,  but  that  efficiency  is  only  slightly  affected  by  change 
in  combustion-chamber  temperature.      A  comparison  with  values 
representing  capacity  (Column  22)  shows  that  as  the  combustion 
chamber  temperature  increases  the  capacity  is  increased. 

20.  The  evaporative  efficiency  as  affected  by  moisture  in  the  coal 
is  not  well  defined  by  the  results  of  the  tests.      While  they  seem 
to  indicate  that  coals  high  in  moisture  generally  give  low  effi- 
ciency it  must  be  remembered  that  high  moisture  is  often  accom- 
panied by  high  ash  content  or  by  poor  mechanical  structure, 
either  of  which  properties  has  a  more  deleterious  effect  on  effi- 
ciency than  moisture.     That  this  is  true  is  emphasized  by  the  fact 
that  the  heat  required  to  evaporate  the  water  in  Illinois  coal  con- 
taining 15  per  cent  moisture  is  but  little  more  than  1.5  per  cent  of 
its  total  calorific  value. 

21.  The  effect  of  sulphur  and  ash  upon  evaporative  efficiency. 
Sulphur  is  an  undesirable  element  in  coal.      It  generally  occurs 
in  combination  with  iron,  as  pyrites,  and  in  combination  with  cal- 
cium as  gypsum.     Of  the  two  sulphur  compounds,  the  former  is 
generally  contained  in  larger  quantity  in  coal  and  is  harmful  be- 
cause it  increases  the  tendency  of  the  coal  to  clinker.     The  clinker- 
ing  is  especially  bad  if  the  percentage  of  ash  is  small  in  proportion 
to  the  sulphur.      In  such  coals  the  pyrites  and  the  ash  fuse  and 
form- a  thin  layer  of  solid  clinker,   which  effectively   stops  the 


FUEL  TESTS  WITH  ILLINOIS  COAL  37 

passage  of  air  through  the  grate,  thus  permitting  the  grate  bars 
to  become  heated  from  the  hot  fuel  bed  just  above.  The  heat 
warps  the  grate  bars  and  the  clinker  has  such  corrosive  action  on 
the  hot  iron  that  destruction  results  in  a  short  time.  When  such 
clinkering  occurs,  any  attempt  to  slice  the  fire  fails  and  only  slow 
and  very  difficult  cleaning  of  the  fires  will  remove  it.  Most  Illi- 
nois coals  having  a  large  sulphur  content  are  also  high  in  ash  so 
that  the  injurious  effect  of  sulphur  is  not  so  pronounced  as  in 
some  other  coals.  In  making  the  tests  it  was  found  that  the  use 
of  steam  served  to  prevent  the  clinker  from  melting  into  the  grate 
when  the  ash  and  sulphur  content  is  large . 

Referring  to  Columns  13,  14,  and  25  of  Tables  7  and  8  the 
decrease  in  efficiency  with  increasing  ash  and  sulphur  will  be  read- 
ily seen.  In  Fig.  7,  which  shows  this  relation  graphically,  efficiency 
is  plotted  against  per  cent  of  ash  plus  sulphur  based  on  dry  coal, 
for  all  tests  run  with  lump,  egg  and  nut  coal.  Although  many  of 
the  plotted  points  lie  at  a  considerable  distance  from  the  average 
line,  its  position  and  direction  are  rather  well  defined.  It  shows 
that  the  efficiency  drops  from  66.5  per  cent  when  the  ash  plus 
sulphur  is  10  percent  to  55  per  cent  when  ash  plus  sulphur  is  30 
per  cent.  For  increases  in  ash  and  sulphur  beyond  18  percent 
the  drop  in  efficiency  is  relatively  rapid. 

22.  The  effect  of  size  on  evaporative  efficiency.  The  discussion 
in  the  preceding  paragraph  does  not  take  into  account  the  fact 
that  size  has  much  to  do  with  the  efficiency  with  which  coal  can 
be  burned,  and  this  is  one  of  the  chief  reasons  for  the  poor  alignment 
of  many  of  the  points.  The  efficiency  shown  by  the  same  tests 
together  with  those  made  with  slack  have  therefore  been  plotted 
against  size,  expressed  in  percent  of  coal  under  i  inch  in  diameter. 
The  resulting  relation  is  shown  in  Fig  8.  Here,  too,  the  points  are 
widely  scattered  but  the  slope  of  the  average  line  is  fairly  well 
fixed.  Thus  a  coal  giving  an  efficiency  of  66  percent  when  10 
percent  of  it  is  under  i-inch  in  diameter,  will  give  an  efficiency 
of  only  62  per  cent  when  60  per  cent  of  it  is  under  i-inch  in  diam- 
eter. 


38 


ILLINOIS   ENGINEERING   EXPERIMENT   STATION 


6        8      10      12      14      16      18      20      22      24      26      28      30     32 

Ash  -f  Sulphur,  Per  Cent  of  Dry  Coal 

FIG.  7    EVAPORATIVE  EFFICIENCY  AS  AFFECTED  BY 

ASH  AND  SULPHUR 


10 


FIG.  8 


50 


60 


20  30  40 

Size  of  Coal,  Per  Cent  Under  i  Inch  * 
EVAPORATIVE  EFFICIENCY  AS  AFFECTED  BY 
SIZE  OF  COAL 


FUEL   TESTS   WITH  ILLINOIS   COAL 


39 


90 

80 
B 
H     70 

o 

1 60 

g    50 

I" 

iS  30 

20 
10 


10  20  30  40  50  60 

Size  of  Coal,  Per  Cent  Under  J  Inch 

FIG.  9    COMBINED  EFFECT  OF  SULPHUR  PLUS  ASH  AND 
SIZE  ON  EVAPORATIVE  EFFICIENCY 

Fig.  9  has  been  drawn  to  show  the  combined  effect  of  sul- 
phur plus  ash  and  size,  on  the  evaporative  efficiency  of  Illinois 
coal.  In  it  lines  have  been  drawn  showing  the  decrease  in  effi- 
ciency with  decrease  in  size  for  coals  having  10,  20  and  30  per 
cent  ash  plus  sulphur  based  on  dry  coal.  There  are,  of  course, 
other  factors  which  affect  efficiency  but  the  results  of  the  present 
tests  seem  to  point  to  these  as  the  most  important.  The  lines 
given  therefore,  may  be  accepted  as  defining  with  considerable 
accuracy,  the  performance  of  Illinois  coal  when  burned  in  a  hand- 
fired  furnace  under  a  water-tube  boiler. 

23.  Comparative  efficiency  resulting  from  the  use  of  washed  and 
unwashed  coal. — It  has  been  shown  that  the  process  of  washing 
Illinois  coal  is  effective  in  reducing  the  ash  and  sulphur  content. 
That  the  evaporative  efficiency  of  the  coal  thus  treated  is  increased 
follows  directly  from  the  facts  just  developed.  The  extent  of  the 


40 


ILLINOIS   ENGINEERING   EXPERIMENT    STATION 


improvement  is  set  forth  by  Table  9.  In  this  table  tests  are 
grouped  in  the  order  of  the  size  of  coal  used.  A  comparison  of 
the  average  values  given  shows  that  where  slack  is  used  washing 
effects  an  increase  of  4.2  per  cent  in  evaporative  efficiency,  2.3 
per  cent  where  nut  is  used,  .7  per  cent  when  run-of-mine  is  used 
and  .6  per  cent  when  lump  is  used.  The  extremely  small  gain  for 


TABLE     9 
COMPARATIVE  EFFICIENCY  OF  WASHED  AND  UNWASHED  COAL 


U.  S.  G.  S. 
Coal 

No. 

Size 

Efficiency 

Unwashed 

Washed 

1 

2 

3 

4 

1 
7C 
10 

Slack 
Slack 
Slack 

58.73 

58  71 
50,12 

61.47 
60.84 
57.82 

60.04 

Average 

55.85 

9A 
12 

R.  o.  m. 
R    o.  m. 

50.28 
62.51 

49.67 

61.48 

57.08 

Average 

56.40 

13 
13 

Nut 
Nut 

65.67 
63.96 

67.93 
66.12 

Average 

64.68 

67.02 

23  A 

18 
18 

Lump 
Lump 
Lump 

66.93 

64.20 
J.9.02 

63.38 

62.12 
63  48 
66.39 

64.00 

Average 

the  last  two  sizes  named  is  explained  by  the  fact  that,  in  the  pro- 
cess of  washing,  the  coal  was  crushed  to  a  size  under  2  inches,  a 
size  which  has  been  shown  not  to  be  so  well  adapted  to  the  kind 
of  grate  and  furnace  used  as  the  larger  size. 

24.  Comparison  of  efficiency  resulting  from  the  use  of  raw  and 
briquetted  coal. — Of  the  112  boiler  tests  made,  15  tests  were  run 
with  briquetted  coal.  Comparing  the  results  shown  in  Table  8 
with  the  results  of  similar  tests  with  raw  coal,  it  will  be  seen  that 
in  most  cases  where  the  raw  coal  is  in  the  form  of  screenings  or 


FUEL  TESTS  WITH  ILLINOIS    COAL 


41 


slack,  briquetting  improves  the  evaporative  efficiency,  but  where 
it  is  in  the  form  of  egg,  nut  or  lump,  but  little  difference  in  perform- 
ance results.  As  in  the  case  of  coal  in  its  natural  state,  effi- 
ciency decreases  as  the  ash  and  sulphur  content  increases.  This 
is  shown  graphically  in  Fig.  10.  The  rather  close  alignment  of 
the  plotted  points  in  this  figure  is  due  principally  to  the  uniform- 
ity in  size  of  the  fuel. 


H     7° 
2 

O    60 


8        10       12       14      16        18       20       22       24       26       28 
Ash  +  Sulphur,  Per  Cent  of  Dry  Coal 

Fi(*.  10    EVAPORATIVE  EFFICIENCY  As  AFFECTED  BY 
ASH  AND  SULPHUR  IN  BRIQUET 


42 


ILLINOIS   ENGINEERING   EXPERIMENT   STATION 


25.  The  evaporative  efficiency  of  Illinois  coal  compared  with 
that  of  coal  from  other  states,  as  shown  by  the  United  States  Geolog- 
ical Survey  tests,  is  presented  in  Table  10.  Only  tests  with  bitumin- 
ous and  semi- bituminous  coal  are  here  included  and  the  average 
values  given  are  based  only  on  tests  which  were  made  under  simi- 


TABLE    10    COMPARATIVE  RESULTS  OBTAINED  FROM  COAL 
FROM  VARIOUS  STATES 


% 

a  ,. 

|| 

ll 

!§ 

o 

—  i 

S      "  ^ 

^  ^ 

T^ 

3 

,3 

*o  > 

Ofe      Q 

Is 

a 

en 

c3 

43    <D 

£~o  o 

O  3 

^  'cd 

o> 

O 

p  Q 

>  ^  ^ 

Q,  O 

State 

Kind  of  Coal 

^ 

^ 

*  0> 

H^Q 

"o^ 

K° 

O 

° 

CD  £ 

c  _,  ^3 

>>i 

P.  ^ 

6 

6 

Pt  O 

£  ~  c 

s  P-* 

,JQ 

fa 

fc 

o>T 

"3  c3  O 

S«^ 

^  w 

>•  r)  P. 

'S'5 

43 

P 

p 

HM 

pq 

1 

2 

3 

4 

5 

6 

7 

8 

Alabama  

Bituminous  

10 

4 

91.9 

8.43 

64.31 

12656 

Arkansas  . 

EJituminous         

8- 

89.3 

9.03 

63.54 

13707 

Colorado  

Bituminous 

1 

1 

71.9 

7.21 

55.36 

12577 

Illinois  .   

Bituminous         

52 

25 

89.6 

7.95 

62.66 

12249 

Iowa 

Bituminous 

5 

5 

90.7 

7.13 

59.55 

11650 

Indiana  

Bituminous  

24 

11 

89.5 

8.23 

63.76 

12549 

Kansas 

Bituminous 

8 

6 

83.4 

8.10 

61.26 

12780 

Kentucky  

Semi-Bituminous  

8 

3 

91.0 

9.77 

65.41 

14417 

Kentucky  

Bituminous 

3 

3 

88.9 

8.37 

62-82 

12883 

Missouri  

Bituminous  

9 

92.2 

7.73 

60.18 

12246 

New  Mexico 

Bituminous  

6 

3 

104.3 

8.28 

64.68 

12507 

Ohio 

Bituminous 

18 

9 

92.2 

8.82 

64.88 

13130 

Pennsylvania 

Bituminous  

18 

9 

89.9 

9.75 

66.22 

14248 

Tennessee  

Bituminous  

24 

9 

102.3 

8.81 

64.18 

13261 

Virginia  

Semi-Bituminous  — 

10 

4 

94.2 

9.73 

65.07 

14436 

West  Virginia  

Bituminousand  Semi- 

Bituminous  

36 

21 

95.5 

9.86 

65.89 

14451 

FUEL   TESTS   WITH  ILLINOIS   COAL  43 

lar  conditions  of  operation.  Column  1  gives  the  name  of  the  state, 
Column  2  the  kind  of  coal,  Column  3  the  number  of  tests  included 
in  the  average,  Column  4  the  number  of  samples  of  coal,  Column 
5  the  average  rate  of  power  developed,  Column  6  the  efficiency  in 
terms  of  equivalent  evaporation  per  pound  of  dry  coal,  Column  7 
the  efficiency  in  per  cent  and  Column  8  the  heating  value  of  the 
coal  in  B.  t.  u.,  per  pound  of  dry  coal.  The  values  given  in  the 
table  show  that  the  average  evaporative  efficiency  of  Illinois  coal 
is  62.66  per  cent.  This  compares  favorably  with  the  results  from 
any  other  coal  tested  and  in  fact  is  nearly  identical  with  the  gen- 
eral average,  63.1. 

VIII    PRODUCER-GAS  TESTS 

26.  The  prod ucer-gas  plant  used  for  the  United  States  Geolog 
ical  Survey  tests  of  Illinois  coal  consists  of  two  Taylor  pressure 
producers  arranged  to  discharge  into  a  single  scrubber,  a 
Westinghouse  three-cylinder  vertical  gas  engine  rated  at  235 
horse-power,  and  a  six-pole,  175  kilowatt  Westinghouse  direct 
current  generator.  Auxiliary  apparatus  was  provided  for  meas- 
uring accurately  the  coal  and  gas,  the  steam  used  by  the  producer, 
and  all  temperatures  and  pressures  necessary  for  a  complete 
determination  of  plant  efficiency.  The  general  arrangement  of 
the  plant  is  well  shown  in  Pig.  11,  and  a  section  through  the  pro- 
ducer in  Fig.  12,  (pp.  45,  46). 

The    principal    dimensions    of   the   producer   plant   are    as 
follows:— 

Producer 

Capacity,  horse-power 250 

Outside  diameter feet 7.0 

Inside  diameter feet 6.5 

Height feet 15 

Area  of  fuel-bed square  feet 38.5 

Diameter  of  gas  delivery  pipe inches 22 

Type  of  feed,  Bildt  automatic  continuous  feed. 

Economizer 

Diameter    feet 3 

Height feet ....  16 . 5 

Number  of  7 -inch  tubtt...  6 


44  ILLINOIS   ENGINEERING   EXPERIMENT   STATION 

Scrubber 

Diameter .feet  ...      8 

Height feet. . . .     20 

Material  used  in  scrubber,  gas-house  coke. 

Tar  extractor 

Speed,  revolutions  per  minute , 1500 

Purifier 

Length  of  sides feet 8 

Height feet....      3.25 

Material  used  in  purifier,  oxidized  iron  filings  and  wood  shavings. 

Gas  holder 

Diameter feet 20 

Height feet. ...     13 

Capacity cubic  feet. . .  4000 

27.  The  tests  were  conducted   alternately   on  the  two  pro- 
ducers, one  being  charged  while  the  other  was  in  operation.    The 
schedule  adopted  involved  two  sixty-hour  runs  per  week.     The 
first  eight  or  twelve  hours  of  each  test  were  used  for  bringing  the 
fuel  bed  to  a  uniform  condition.      During  this  preliminary  run- 
ning,   observations   were   made  as  in  the  regular  tests,  but  the 
record  data  include  only  the  last  48  or  50  hours,  when  the  run- 
ning conditions  were  maintained  as  uniform  as  possible.     Special 
attention  was  directed  to  the  accurate  measurements  of  the  coal 
actually  used  and  charts  and  checking  devices  were  introduced 
for  this  purpose. 

Owing  to  the  lack  of  reliability  in  the  operation  of  the  gas 
engine,  many  of  the  tests  made  at  the  beginning  of  the  series 
were  only  of  a  few  hours'  duration;  later,  however,  no  difficulty 
was  experienced  in  starting  the  engine  and  continuing  it  in  opera- 
tion for  a  period  of  120  hours.  During  this  time  two  different 
coals  were  tested.  Altogether  30  tests  were  made  involving  the 
use  of  23  different  samples  of  Illinois  coal. 

28.  Results  of  the  tests. — The  more  important  observed  and 
calculated  results  of  the  tests  are  given  in  Table  11.    Column  1  of 
this  table  is  the  laboratory  number  of  the  test,  Column  2  the 
U.  S.  G.  S.  number  of  the  sample  tested  and  Column  3  the  size  of  the 
coal  tested.    The  proximate  analyses  of  the  coal  as  fired  are  given 
in  Columns  4  to  8  and  the  heating  value  in  B.   t.  u.  per  pound  of 
dry  coal  is  given  in  Column  4.      The  brake  horse-power  given  in 
Column  10  is  the  power  delivered  by  the  gas  engine.     Column  11 
is  the  cubic  feet  of  gas  delivered  by  the  producer  per  hour,    in 
terms  of  standard  gas,    that  is,   gas  at  atmospheric  pressure  and 
60°  F.  temperature.      Column  12  is  the  calorific  value  of  the  gas 
expressed  in  B.  t.  u.  per  cubic  foot  of  standard  gas.      Column  13 


FUEL   TESTS   WITH   ILLINOIS   COAL 


45 


£ 


QQ 


46 


ILLINOIS   ENGINEERING    EXPERIMENT    STATION 


FIG.  12    ELEVATION  SHOWING  GENERAL  ARRANGEMENT  OF 
PRODUCER-GAS  PLANT    (Prof.  Paper  48,  p.  983) 


FUEL   TESTS   WITH   ILLINOIS   COAL 


47 


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48 


ILLINOIS   ENGINEERING   EXPERIMENT   STATION 


is  the  cubic  feet  of  standard  gas  per  pound  of  dry  coal.  Column 
14  is  the  B.  t.  u.  contained  in  the  gas  per  pound  of  dry  coal  fired. 
This  value  divided  by  the  heating  value  of  the  coal  (Column  9) 
equals  the  thermal  efficiency  of  the  producer.  Column  15  is  the 
pounds  of  dry  coal  consumed  by  the  producer  per  brake-horse- 
power available  for  outside  purposes. 

In  comparing  the  results  of  the  producer  tests  as  set  forth  in 
Table  11,  too  much  emphasis  can  not  be  given  the  fact  that  they 
were  subjected  to  absolutely  no  refinements.  With  the  exception 
of  three  coals  one  test  only  has  been  made  on  each  kind  and  grade, 
and  the  result  of  each  test  has,  to  a  great  extent,  depended  upon 
the  ability  of  the  operator  to  discover  the  best  methods  of  handling 
a  given  coal  within  the  8  or  10  hours  allowed  preliminary  to  the  offi- 
cial test.  Moreover,  all  tests  were  made  on  one  type  and  in  one 
size  of  producer,  a  type  designed  primarily  for  anthracite  coal, 
and  in  carrying  out  the  plan  of  the  tests  more  effort  was  made  to 
develop  the  required  power  than  to  observe  the  proper  relation 
between  the  gas  producing  qualities  of  the  coal  and  the  area  of 
the  fuel  bed. 

In  spite  of  all  these  restrictions  it  is  the  opinion  of  those  who 
were  in  charge  of  the  tests  that  certain  general  relationships  have 


100 
90 
80 
70 
60 
50 


3   40 


30 


fe   20 

o  10 


10 


1(1 


18 


12  14 

Ash  Per  Cent 

FIG.  13    CUBIC  FEET  OF  GAS  PER  POUND  OF  COAL  AS  AFFECTED 
BY  PER  CENT  OF  ASH  IN  DRY  COAL 


FUEL  TESTS  WITH  ILLINOIS   COAL  49 

been  fairly  well  established.  They  may  be  subject  to  modification 
in  the  light  of  future  investigations,  but  the  conclusions  to  be 
drawn  from  them  are  sufficiently  significant  for  presentation. 

29.  Efficiency  as  affected  ~by  ash  in  the  coal. — The  cubic  feet  of 
gas  delivered  by  the  producer  per  pound  of  coal  fired  is,  perhaps, 
the  most  convenient  measure  of  efficiency.     Referring  to  Column 
13,  Table  11,  it  will  be  seen  that  in  general  as  the  ash  in  the  coals 
increases  this  quantity  decreases.       The  exact  relation  for  all 
tests  made  at  full  load  is  shown  graphically  in  Fig.  13.     In  this 
figure,  cubic  feet  of  standard  gas  per  pound  of  dry  coal  is  plot- 
ted against  ash  expressed  in  per  cent  of  dry  coal.      The  average 
line  is  drawn  so  as  to  include  as  many  of  fche  plotted  points  as 
possible.     It  shows  that  when  the  coal  contains  8  per  cent  ash 
the  output  of  the  producer  is  67  cubic  feet  per  pound  of  dry  coal 
fired  and  that  when  ash  is  20  per  cent  the  output  is  decreased  to 
50  cubic  feet. 

30.  Efficiency  as  affected  by  calorific   value  of  the   coal. — The 
cubic  feet  of  gas  per  pound  of  dry  coal  plotted  against  B.  t.  u. 
per  pound  of  dry  coal  for  all  tests  made  at  full  load  is  shown  in 
Fig.  14.     Since  the  heating  value  of  Illinois  coal  is  very  nearly 
inversely  proportional  to  the  ash  content  the  relation  shown  is 
merely  a  restatement  of  the  facts  brought  out  in  Fig.  13.     The 
points,   however,    fall   in   better    alignment.      It   appears   from 
the  curve  that  the  output  of  gas  in  cubic  feet  per  pound  of  coal 
increases  from  49  when  the  calorific  value  is  1 1000  B.  t.  u.  per 
pound  of  dry  coal,  to  65  when  the  calorific  value  is  13000.     Fig.  15 
shows  the  efficiency  expressed  in   per  cent  plotted  against  the 
heating  value  of  the  coal.     Here  the  same  rise  in  efficiency  is 
again  shown.     The  average  value  at  11000  is  58  per  cent  and  at 
13000  it  is  76  per  cent. 


50 


ILLINOIS  ENGINEERING   EXPERIMENT   STATION 


100 


o    90 

O 

§    80 


7 


- 


B  10 

o 


11000 


12000  13000 

B.  t,  u.  per  pound  of  Coal 


14000 


FIG.  14    CUBIC  FEET  OF  GAS  PER  POUND  OF  COAL,  AS  AFFECTED 
BY  CALORIFIC  VALUE  OF  THE  COAL 


100 


W  10 


11000 


12000  13000 

B.  t.  u.  per  pound  of  Coal 


14000 


FIG.  15    EFFICIENCY  OF  PRODUCER  AS  AFFECTED  BY  CALORIFIC 
VALUE  OF  THE  COAL 


FUEL,  TESTS  WITH  ILLINOIS  COAL 


51 


31.  A  comparison  of  Illinois  coal  with  other  bituminous  coals. 
A  condensed  summary  of  the  more  important  items  relating  to 
Illinois  coals  compared  with  those  relating  to  all  other  bituminous 
coals  tested,  is  presented  in  Table  12.  The  average  values  given 

TABLE    12 

A  COMPARISON  OF  ILLINOIS  COAL  WITH  BITUMINOUS  COALS 
FROM  OTHER  STATES  FOR  GAS  PRODUCER  SERVICE 


Average  of 
Tests  with 
111.  Coal 

Average  of 
All  Tests 
with  Bitum- 
inous Coal 

Composition  of  fuel,  per  cent: 
Moisture  

10  84 

6  82 

Volatile  matter      .        .        

33  06 

33  06 

Fixed  carbon  

44  06 

49  80 

Ash  

12  04 

10  32 

Sulphur 

3  15 

2  41 

B.  t.  u,  per  pound  of  dry  coal  ... 

12000 

13150 

Composition  of  gas,  volume  per  cent: 
Carbon  dioxide        .  .  . 

9  60 

9  84 

Oxygen  .     .  . 

03 

04 

Nitrogen  

56  81 

55  60 

Hydrocarbons  

3  21 

3  30 

Carbon  monoxide         .     ... 

18  31 

18  28 

Hydrogen  

12  01 

12  90 

B.  t.  u,  per  foot  of  standard  gas 

146  5 

152  1 

Cubic  feet  of  standard  gas  per  pound  of  dry  coal 

59  1 

64  7 

Pounds  of  dry  coal  per  brake  horse  power,  hour  

1.36 

1  26 

are  computed  only  from  tests  in  which  the  producer  was  operated 
at  its  rated  capacity.  It  will  be  noted  that  while  the  analysis 
shows  that  the  Illinois  coal  contains  4  per  cent  more  moisture  and 
2i  per  cent  more  ash  the  quality  of  the  gas  produced  is  but 
slightly  inferior.  Thus  the  heating  value  is  146.5  B.  t.  u.  per 
foot  of  standard  gas  when  Illinois  coal  is  used  and  152.1  when 
other  bituminous  coal  is  used.  The  output  of  gas,  measured  in 
cubic  feet  per  pound  of  dry  coal,  is  59.1  in  the  one  case  and  64.7 
in  the  other.  Comparing  the  efficiency  at  the  engine  it  will  be 
seen  that  it  requires  1.36  pounds  of  Illinois  coal  to  develop  a 
horse- power  and  1.26  pounds  when  other  bituminous  coals  are 
used.  This  comparison  is  by  no  means  unfavorable  and  consid- 
ering the  lower  selling  prices  which  prevail  for  Illinois  coals  the 
very  slight  difference  in  efficiency  is  almost  insignificant. 

32.  Relative  results  of  steam  and  producer-gas  tests. — From 
theoretical  considerations  it  may  easily  be  shown  that  it  is  pos- 
sible for  the  gas  engine  to  utilize  a  much  larger  amount  of  the 


ILLINOIS   ENGINEERING   EXPERIMENT    STATION 

RELATIVE  AMOUNT  OF  ILLINOIS  COAL  USED  BY  STEAM  AND 
PRODUCER  PLANT 

POUNDS  PER  BRAKE  HORSE-POWER  HOUR 


OQ 


Steam  Plant 


Producer  Plant 


Ratio 


*7A 
11C 

7C 
27 
*7B 
190 
21 

*23B 
*6B 

4 

9B 
26 

8 

3 

23A 
29B 
22A 
16 
15 
14 
13 
18 
30 
25 
10 
24B 
19B 
11A 
*11D 
*11D 


|  i 


0 


01234 

*  No  producer  test. 
FIG.  16    RELATIVE  COAL  CONSUMPTION  IN  GAS  AND  STEAM  PLANTS. 


FUEL  TESTS   WITH  nJ#K#ISr-@OAI/-J  'J    53 

heat  supplied  than  the  steam  engine.     The  results  of  the  present 
tests  show  how  much  of  this  saving  is  realized  in  practice. 

The  ratios  of  the  total  coal  per  brake  horse- power  hour  re- 
quired by  the  steam  plant  and  producer  gas  plant  under  full 
load  conditions  are  presented  in  Fig.  16.  The  values  representing 
producer  plant  performance  are  those  of  Column  15,  Table  11, 
and  those  representing  steam  plant  performance  are  calculated 
from  those  of  Column  25,  Table  8,  allowing  85  per  cent  as  the 
efficiency  of  the  dynamo.  It  will  be  seen  that  the  maximum  ratio 
is  3.13  and  the  minimum  1.50  while  the  average  is  2.61. 


54     l  iLilNbW  ENGINEERING    EXPERIMENT   STATION 


UNITED  STATES  GEOLOGICAL  SURVEY  PUBLICATIONS  ON  FUEL  TESTING 

The  following  publications,  except  those  to  which  a  price  is  affixed,  can  b^  obtained  free 
by  applying  to  the  Director.  Geological  Survey,  Washington.  D.  C.  The  priced  publications 
can  be  purchased  from  the  Superintendent  of  Documents,  Government  Printing  Office,  Wash- 
ington. D.  C. 

Jhdletin  No.  261.  Preliminary  report  on  the  operations  of  the  coal-testing  plant  of  the 
Unit'  d  States  Geological  Survey  at  the  Louisiana  Purchase  Exposition,  in  St.  Louis,  Mo.,  1904; 
E.  W.  Parker,  J.  A.  Holmes,  M.  R.  Campbell,  committee  in  charge.  1905.  172  pp.  10  cents. 

Professional  Paper  No.  48.  Report  on  the  operations  of  the  coal-testing  plant  of  the 
United  States  Geological  Survey  at  the  Louisiana  Purchase  Exposition,  St,  Louis,  Mo.,  1904; 
E.  W.  Parker,  J.  A.  Holmes,  M.  R.  Campbell,  committee  in  charge.  1906-  In  three  parts.  1492 
pp.  13  pis  $1.50. 

Bulletin  No,  290.  Preliminary  report  on  the  operations  of  the  fuel-testing  plant  of  the 
United  States  Geological  Survey  at  St.  Louis,  Mo.,  1905,  by  J-  A.  Holmes.  1906.  210  pp.  20  cents. 

Bulletin  No.  323.  Experimental  work  conducted  in  the  chemical  laboratory  of  the  United 
States  fuel-testing  plant  at  St.  Louis,  Mo.,  January  1,  1905,  to  July  31,  1906.  by  N.  W.  Lord.  1907. 
49pp. 

Bulletin  No.  3S5.  A  study  of  four  hundred  steaming  tests,  made  at  the  fuel-testing  plant, 
St.  Louis,  Mo.,  1904,  1905,  and  1906.  by  L.  P.  Breckenridge.  1907.  196  pp. 

Bulletin  No.  332.  Report  of  the  United  States  fuel-testing  plant  at  St.  Louis,  Mo., 
January  1,  1906,  to  June  30,  1907;  J.  A.  Holmes,  in  charge.  1908.  299  pp. 

Bulletin  No.  334.  The  burning  of  coal  without  smoke  in  boiler  plants:  a  preliminary  re- 
port, by  D.  T.  Randall.  1908.  26  pp. 

Bulletin  No.  336.  Washing  and  coking  tests  of  coal  and  cupola  tests  of  coke,  by  Richard 
Moldenke,  A.  W.  Belden.  and  G.  R.  Delamater.  1908.  76  pp. 

Bulletin  No.  339-  The  purchase  of  coal  under  Government  and  commercial  specifications 
on  the  basis  of  its  heating  value,  with  analyses  of  coal  delivered  under  Government  contracts, 
by  D.  T.  Randall.  1908.  27  pp. 

Bulletin    No-    343.    Binders  for  coal  briquets,  by  J.  E.  Mills.    1908.    56pp. 

Bulletin  No.  362.  Mine  sampling  and  chemical  analyses  of  coals  tested  at  the  United 
States  fuel-testing  plant,  Norfolk,  Va..  in  1907,  by  J.  S.  Burrows.  1908.  23  pp. 

Bulletin  No,  363.  Comparative  tests  of  run-of-mine  and  briquetted  coal  on  locomotives, 
by  W.  V.  M.  Goss.  1908.  57  pp. 

Bulletin  No.  366.  Tests  of  coal  and  briquets  as  fuel  in  house-heating  boilers,  by  D.  T. 
Randall.  1908.  44  pp. 

Bulletin  No.  368.  Washing  and  coking  tests  of  coal,  by  A.  W.  Belden,  G.  R.  Delamater 
and  J.  W.  Groves.  1908.  53  pp. 


PUBLICATIONS  or  THE  ENGINEERING  EXPERIMENT  STATION 

Bulletin  No.  1.  Tests  of  Reinforced  Concrete  Beams,  by  Arthur  N.  Talbot.  1904.  (Out 
of  print.) 

Circular    No.    1.    High-Speed  Tool  Steels,  by  L.  P.  Breckenridge.  1905.     (Out  of  print.) 

Bulletin  No.  2.  Tests  of  High-Speed  Tool  Steels  on  Cast  Iron,  by  L.  P.  Breckenridge 
and  Henry  B .  Dirks.  1905.  ( Out  of  print. ) 

Circular   No.    2.    Drainage  of  Earth  Roads,  by  Ira  O.  Baker.    1906.    (Out  of  print.) 

Circular  No.  3.  Fuel  Tests  with  Illinois  Coal.  (Compiled  from  tests  made  by  the  Tech- 
nologic Branch  of  the  U-  S-  G.  S..  at  the  St.  Louis,  Mo.,  Fuel  Testing  Plant,  1904-1907,  by  L.  P. 
Breckenridge  and  Paul  Diserens.  1909. 

Bulletin  No.  3.  The  Engineering  Experiment  Station  of  the  University  of  Illinois,  by 
L.  P.  Breckenridge.  1906.  (Out  of  print.) 

Bulletin  No.  4.  Tests  of  Reinforced  Concrete  Beams.  Series  of  1905,  by  Arthur  N. 
Talbot.  1906. 

Bulletin  No.  5.  Resistance  of  Tubes  to  Collapse,  by  Albert  P.  Carman.  1906.  ( Out  of 
vrint.) 

Bulletin  No.  6.  Holding  Power  of  Railroad  Spikes,  by  Roy  I.  Webber.  1906.  (Out  of 
print.) 

Bulletin  No.  7.  Fuel  Tests  with  Illinois  Coals,  by  L.  P.  Breckenridge,  S.  W.  Parr  and 
Henry  B.  Dirks.  1906.  (Out  of  print.) 

Bulletin  No.  8.  Tests  of  Concrete:  I.  Shear;  II.  Bond,  by  Arthur  N.  Talbot.  1906.  (Out 
of  print.) 

Bulletin  No.  9.  An  Extension  of  the  Dewey  Decimal  System  of  Classification  Applied 
to  the  Engineering  Industries,  by  L.  P.  Breckenridge  and  G.  A.  Goodenough.  1906. 

Bulletin  No.  10.  Tests  of  Concrete  and  Reinforced  Concrete  Columns.  Series  of  1906,  by 
Arthur  N.  Talbot.  1907.  (Out  of  print.) 

Bulletin  No.  11.  The  Effect  of  Scale  on  the  Transmission  of  Heat  through  Locomotive 
Boiler  Tubes,  by  Edward  C.  Schmidt  and  John  M.  Snodgrass.  1907.  (Out  of  print.) 

Bulletin  No.  12.  Tests  of  Reinforced  Concrete  T-beams.  Series  of  1906.  by  Arthur  N. 
Talbot.  1907.  (Out  of  print.) 

Bulletin  No.  13.  An  Extension  of  the  Dewey  Decimal  System  of  Classification  Applied 
to  Architecture  and  Building,  by  N.  Clifford  Ricker.  1907. 

Bulletin  No.  14.  Tests  of  Reinforced  Concrete  Beams,  Series  of  1906,  by  Arthur  N. 
Talbot.  1907.  (Out  of  print.) 

Bulletin    No.  15.    How  to  Burn  Illinois  Coal  without  Smoke,  by  L.  P.  Breckenridge.  1908. 

Bulletin    No.  16.    A  Study  of  Roof  Trusses,  by  N.  Clifford  Ricker'  1908. 

Bulletin  No.  17.  The  Weathering  of  Coal,  by  S.  W.  Parr,  N.  D.  Hamilton,  and  W.  F. 
Wheeler.  1908.  (Out  of  print.) 

Bulletin    No.  18.    The  Strength  of  Chain  Links,  by  G.  A.  Goodenough  and  L.  E.  Moore.  1908. 

Bulletin  No.  19.  Comparative  Tests  of  Carbon,  Metallized  Carbon  and  Tantalum  Fila- 
ment Lamps,  by  T.  H.  Amrine.  1908. 

Bulletin  No.  20.  Tests  of  Concrete  and  Reinforced  Concrete  Columns,  Series  of  1907,  by 
Arthur  N.  Talbot.  1908. 

Bulletin    No.  21.    Tests  of  a  Liquid  Air  Plant,  by  C.  S.  Hudson  and  C.  M.  Garland.    1908 

Bulletin  No.  22.  Tests  of  Cast-Iron  and  Reinforced  Concrete  Culvert  Pipe,  by  Arthur  N. 
Talbot.  1908. 

Bulletin    No.  23.    Voids,   Settlement  and  Weight  of  Crushed  Stone,  by  Ira  O.  Baker.  1908. 

Bulletin  No.  24.  The  Modification  of  Illinois  Coal  by  Low  Temperature  Distillation,  by 
S.  W.  Parr  andC.  K.  Francis.  1908. 

Bulletin  No.  25.  Lighting  Country  Homes  by  Private  Electric  Plants,  by  T.  H. 
Amrine.  1908. 

Bulletin  No.  26.  High  Steam-Pressures  in  Locomotive  Service.  A  Review  of  a  Report  to 
the  Carnegie  Institution  of  Washington.  By  W.  F.  M.  Goss.  1908. 

Bulletin  No.  27.  Tests  of  Brick  Columns  and  Terra  Cotta  Block  Columns,  by  Arthur  N. 
Talbot  and  Duff  A.  Abrams.  1909. 

Bulletin  No.  28,  A  Test  of  Three  Large  Reinforced  Concrete  Beams,  by  Arthur  N. 
Talbot.  1909. 

Bulletin  No.  29.  Tests  of  Reinforced  Concrete  Beams:  Resistance  to  Web  Stresses, 
by  Arthur  N.  Talbot.  1909. 

Bulletin  No.  30.  On  the  Rate  of  Formation  of  Carbon  Monoxide  in  Gas  Producers,  by  J. 
K.  Clement.  L.  H.  Adams,  and  C.  N.  Haskins  1909. 

Bulletin    No,    31.    Fuel  Tests  with  House-heating  Boilers,  by  J.  M.  Snodgrass.    1909. 

Bulletin    No.    32.    The  Occluded  Gases  in  Coal,  by  S.  W.  Parr  and  Perry  Barker.    1909. 


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